S.W.
Please give this change some time! Your kids will play on your emotions on purpose! My daughter usually loved going to daycare, but I would see other kids cling and cry and their mothers would be upset. A MINUTE after the mother left, the kids were happily playing with friends. The daycare teachers told me they see this all the time!
Every decision we make has sacrifices. Staying home with your kids gives you satisfaction, so does your work. You say they are at daycare FOUR days a week, so you have found some balance already. Very soon the two oldest will be in school most of the day, five days a week, whether you are at work or not. You can be an effective, wonderful, loving parent and still have a career. What do you want for your children when they grow up? You are modeling, especially for your daughters, what is possible for them.
I work with unemployed people as a Career Counselor. Many, many women find themselves divorced/widowed/separated and unable to find work that can support them (much less be enjoyable) because of being out of the workplace for even a few years. They counted on their husbands to support them with no thought for the possibility that they would need to be self-sufficient.